1. Field of the Invention
The present invention relates generally to magnetic head fabrication methods, and more particularly to methods and devices for determining the physical characteristics of magnetic heads during the fabrication thereof, particularly determination of the P2B width of magnetic heads during the fabrication thereof on wafer substrates.
2. Description of the Prior Art
Magnetic heads for hard disk drives are manufactured in large quantities on wafer substrate surfaces, using fabrication methods that are well known to those skilled in the art. One of the most critical dimensions for such magnetic heads is the width of the base of the P2 pole tip (herein termed P2W), because the P2W width generally determines the width of the data track that is written by the magnetic head after it is fabricated and installed in a disk drive device. Therefore, for quality control purposes it is desirable to measure the P2W width of a statistically significant sample of the magnetic heads being fabricated upon the substrate surface following the fabrication of the P2 pole tips. However, the shape of the fabricated P2 pole tip on the substrate substantially screens efforts to measure the P2W width of the pole tip at its base. This is particularly true where the P2 pole tip is fabricated with a larger width at its top portion than at its base, which is generally the case where the pole tip is fabricated utilizing photolithographic techniques. Because the top of the pole tip is wider than the pole tip base, a top down scanning electron microscope (SEM) cannot accurately measure the base width (the P2W width), and SEM measurements are therefore currently made at an oblique angle. These oblique P2W width measurements are time-consuming, expensive and can only be performed on a small statistical sample of the many magnetic heads fabricated on the wafer surface. The present invention solves this problem by fabricating a test P2 pole tip in the kerf, or saw cut, regions of the wafer surface in a manner that allows unobstructed top down SEM measurement of the test P2 pole tip base. Because the test pole tip is fabricated immediately next to the actual magnetic head, and because it is fabricated with the same materials, conditions and topology as the actual magnetic head, the measurement of the width of the test pole tip base constitutes an accurate P2W measurement of the base of the actual P2 pole tip of the magnetic head.
The present invention is a method for determining a characteristic of a magnetic head during its fabrication process on the surface of a wafer substrate. The method involves the fabrication of a test magnetic pole artifact in a field area of the substrate surface adjacent to the actual magnetic pole that is being fabricated. A test pole structure is fabricated simultaneously with the actual pole utilizing the same fabrication conditions and parameters, such that the test pole is nearly identical to the actual pole. During a field etch step undertaken in the fabrication of the actual pole, portions of the test pole structure are removed, leaving a test pole artifact on the wafer surface. The test pole artifact can be easily measured as an accurate indication of characteristics of the actual magnetic pole that are difficult to measure directly, thereby saving time and expense in the magnetic head fabrication process. The present invention is particularly suited to determining the width of the base of the P2 pole tip of a magnetic head, where a measurement of the base of the actual magnetic head pole tip is made difficult by the presence of the pole tip, and the test artifact is easily measured because the test pole tip structure has been etched away, leaving only the artifact for measurement, as a determination of the width of the base of the P2 pole tip of the magnetic head. A plurality of test pole structures can be fabricated upon various portions of the surface of the wafer to provide measurements from the various portions of the surface, whereby such problems as phototool distortion, wafer and chuck flatness, resist coating non-uniformities and the like can be determined.
It is an advantage of the magnetic head fabrication method of the present invention that a characteristic of a magnetic head can be determined indirectly while the head is disposed on a substrate surface during the fabrication process.
It is another advantage of the magnetic head fabrication method of the present invention that a characteristic of a magnetic head can be determined by measurement of a test device fabricated proximate the magnetic head upon the surface of a substrate.
It is a further advantage of the magnetic head fabrication method of the present invention that the width of the base of a P2 pole tip of the magnetic head can be determined rapidly and inexpensively.
It is yet another advantage of the magnetic head fabrication method of the present invention that a test magnetic pole structure is fabricated proximate the actual magnetic head under identical process conditions, such that a pole tip of the test magnetic pole structure is nearly identical to the pole tip of the actual magnetic head.
It is yet a further advantage of the magnetic head fabrication method of the present invention that a test magnetic pole tip structure is fabricated proximate an actual magnetic P2 pole tip, and that the test pole tip is removed during a process step to leave a test artifact that is easily and inexpensively measured as an indication of the base width of the P2 pole tip.
It is still a further advantage of the method for fabricating a magnetic head of the present invention that a plurality of test magnetic pole structures can be fabricated at various locations on the surface of a substrate, such that phototool distortion, wafer and chuck flatness, resist coating non-uniformities and the like can be determined.
These and other features and advantages of the present invention will no doubt become apparent to those skilled in the art upon reading the following detailed description which makes reference to the several figures of the drawings.